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winding inductors

2997 Views 7 Replies 3 Participants Last post by  brucek
Hello all
I would like some input re inductor winding I am at present putting together a 7.1 av system, I have designed the speakers using bass box pro and xo calculator the towers are in a mtm format which has a bass driver in the lower dived section it is to crossover at 240hz
According to the calculated inductor from xo pro I need to wind a coil of awg 16# at 5.5mh this is a large component that would offer some resisentce of flow to the speakers, I would also assume that there would be a decrease in efficiency (db)
That aside has anyone had any success in producing there own coils
I spent approximately four hours yesterday winding and have fabricated 10 coils
The hardest part of this process is getting the wire to feed onto the bobbin evenly and to keep count at the same time
I also noticed that if they are no wound tightly enough there is a lot of differential in meter readings, after some time I managed to get good results but I still had to unwind wire to get back to the desired mh readings
I will mention that if I zipped tied them really tightly together, the meter readings would increase which is probably why we pay so much for the perfect lay inductors
I had to pick up some more wire to day and was talking with the owner of the rewind business I mentioned re problems with inconsistency in readings and he said to me why don’t you wind so far then use the alligator clips on your meter to scratch into the varnish and take a reading that way you will not use so much wire up by having to trim each time you wind just a light spray of varnish to cover your scratches and away you go (tricks of the trade)
Has any one used two pack glue to secure the coils once they have finished winding as it takes a lot of cable ties to secure my coils?
Has anyone fabricated the impedance equalization circuits that are suggested in xo pro software as these can become very expensive when you add up all of the bipolar caps, inductors and resistors necessary to complete the circuit, I was considering building the main crossover then adding the equalization circuits after to see if there is any audible difference as I am not privee to expensive metering equipment
Any input would be greatly appreciated
Cheers to more beers Speedie
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Are you talking about a Zobel network for impedance equalization? If so, those are handy to flatten out the woofer's "tail". Sometimes a woofer's rising response can mess up the crossover at higher frequencies. Not an issue if the woofer is incabable of producing any noise there, but some metal cone woofers can play some pretty shrill notes up high (mostly distortion and cone breakup modes), obviously which you don't want.

I've gotten in the habit of adding one to a woofer every time before I do any testing. Just add the Zobel, remeasure the impedance and design the crossover from there. That being said, you might be able to live without one, if cost is an issue. I would try it on a stereo pair and see how it measures/sounds with and without the circuit. Then you can make the call whether it is needed or worth the cost.

Good luck.
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brucek thanks for the link but have already been there
looks like he is winding 22-24# wire (the hose is too small for the required flow)do you have any first hand offerings
cheers Speedie
If you have used bass box pro it provides an equilazation circuit that is to flatten out the predicted driver response it is in the bypass or shut area of the crossover
would you deem this a zobel circuit
with referance to costs i am a bang for your buck sort of bloke
if warranted i would not hesitate to spend on components to obtain quality
cheers for your input
just looked at your cv
it would appear that you would have first hand experince
we can only talk about what we know and my knowlegde is not electronics
thermo dynamics (it is only hot where your hands is )
thanks Speedie
Hello again everyone
Thought that I would include some snaps of my coil winding gadget
I bought some 25mm dowel of the hardware store then used a lathe to fabricate three separate wooden widths which were bored through the centre axis to accept a section of 6mm all thread rod.
It was also a bonus having a friend that has a laser cutting machine because we cut three different size retainers so I could use different wire gauge in varying bobbin lengths.
As you can see from the snaps the coils appear to be sound in construction but to date I haven’t used them in my speaker project which is still in its construction stage
I hope that this might to inspire someone else to try there hand at coil fabricating
I feel that the more dissemination of information can only assist others who are like minded
Cheers to more! Beers Speedie


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